//
// Copyright (C) 2016 Google, Inc.
//
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#include "hlslTokenStream.h"

namespace glslang {

void HlslTokenStream::pushPreToken(const HlslToken& tok)
{
    assert(preTokenStackSize < tokenBufferSize);
    preTokenStack[preTokenStackSize++] = tok;
}

HlslToken HlslTokenStream::popPreToken()
{
    assert(preTokenStackSize > 0);

    return preTokenStack[--preTokenStackSize];
}

void HlslTokenStream::pushTokenBuffer(const HlslToken& tok)
{
    tokenBuffer[tokenBufferPos] = tok;
    tokenBufferPos = (tokenBufferPos+1) % tokenBufferSize;
}

HlslToken HlslTokenStream::popTokenBuffer()
{
    // Back up
    tokenBufferPos = (tokenBufferPos+tokenBufferSize-1) % tokenBufferSize;

    return tokenBuffer[tokenBufferPos];
}

// Load 'token' with the next token in the stream of tokens.
void HlslTokenStream::advanceToken()
{
    pushTokenBuffer(token);
    if (preTokenStackSize > 0)
        token = popPreToken();
    else
        scanner.tokenize(token);
}

void HlslTokenStream::recedeToken()
{
    pushPreToken(token);
    token = popTokenBuffer();
}

// Return the current token class.
EHlslTokenClass HlslTokenStream::peek() const
{
    return token.tokenClass;
}

// Return true, without advancing to the next token, if the current token is
// the expected (passed in) token class.
bool HlslTokenStream::peekTokenClass(EHlslTokenClass tokenClass) const
{
    return peek() == tokenClass;
}

// Return true and advance to the next token if the current token is the
// expected (passed in) token class.
bool HlslTokenStream::acceptTokenClass(EHlslTokenClass tokenClass)
{
    if (peekTokenClass(tokenClass)) {
        advanceToken();
        return true;
    }

    return false;
}

} // end namespace glslang
